• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1011-1012
• /
• 2011

본 연구에서는 자성유체를 기반으로 마이크로 스케일 유체를 이동시키기 위한 pump를 모델링하고 실험을 통해 동작을 확인한다. 탄성체와 자성유체로 구성된 횡경막이 연속적으로 움직이는 형태의 액츄에이터는 pump와 같은 움직임을 일으키는데, 이 때 움직이는 유체의 양은 매우 극소량으로 제어 가능하며, 액적의 이동속도는 자성유체를 통한 횡경막의 반복적인 움직임의 속도에 의해 결정된다. 자력에 의한 횡경막의 변위에 따른 액적의 양을 유추하고 고안된 마이크로 스케일의 pump의 예측된 움직임을 실제 제작하여 비교 관찰하고자 한다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 학술대회
• /
• pp.221-226
• /
• 2008

Numerical simulation is performed for microdroplet deposition on a pre-patterned micro-structure. The level-set method for tracking the liquid-gas interface is extended to treat the immersed (or irregular-shaped) solid surface. The no-slip condition at the fluid-solid interface as well as the matching conditions at the liquid-gas interface is accurately imposed by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to improve the patterning accuracy.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년 추계학술대회논문집
• /
• pp.221-226
• /
• 2008

Numerical simulation is performed for microdroplet deposition on a pre-patterned micro-structure. The level-set method for tracking the liquid-gas interface is extended to treat the immersed (or irregular-shaped) solid surface. The no-slip condition at the fluid-solid interface as well as the matching conditions at the liquid-gas interface is accurately imposed by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to improve the patterning accuracy.

• 한국철도학회논문집
• /
• 제9권6호
• /
• pp.625-629
• /
• 2006

This paper describes the effect of the droplet breakup process on fire suppression using a water-mist system, which is considered as a alternative to sprinkler fire suppression system. In the evolution of the water-mist, the droplet breakup process is an important phenomenon because it may significantly affect the droplet evaporation rate. The Fire Dynamics Simulator (FDS, Ver. 4.0) code, which is widely used for the simulation of fire dynamics, is used for the present simulation, and it is modified to consider the droplet breakup phenomena. The Prediction by the modified code shows good agreement with experimental data for the temperature. The original FDS predicts higher temperature about $30^{\circ}C$ than experimental data. From the results, it is concluded that the droplet breakup phenomena must be considered for more precise simulation of fire suppression process.

• 한국가시화정보학회지
• /
• 제8권4호
• /
• pp.43-47
• /
• 2010

We demonstrate the droplet bistability in a microchannel which has two symmetric necks that operate as capillary valves. It is shown that there are certain flow conditions, determined by droplet velocity and droplet size, to achieve bistability. Droplet bistabililty allows simple but precise control of droplet at a bifurcation channel. Therefore, by an appropriate channel design to induce droplet bistability, we can distribute droplets at a junction passively in the manner of perfect alternation and perfect switching in the choice of the outlets.

• 한국가시화정보학회지
• /
• 제18권2호
• /
• pp.46-50
• /
• 2020

On-demand droplet generation with tunable droplet volume is fundamental in many droplet microfluidic applications. In this work, we propose an acoustofluidic method to produce water-in-oil droplets with prescribed volume in an on-demand manner. Surface acoustic waves produced from a slanted interdigital transducer are coupled with parallel laminar streams of dispersed and continuous phase fluids. Acoustic radiation force acting on the fluid interface enable generation of droplets in a microfluidic chip. We expect that the proposed acoustofluidic droplet generation method will serve as a promising tool for on-demand droplet generation with on-chip droplet volume control.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2022년도 봄 학술논문 발표대회
• /
• pp.251-252
• /
• 2022

The microfluidic controlled droplet manufacturing system is one of the most powerful methods for capsule manufacturing. The microfluidic control method can control the type and size of the capsule by changing the size and configuration of the channel. In addition, by increasing the number of channels, capsules of uniform size can be mass-produced. In this paper, a capsule manufacturing system including flow-focusing and T junction method was designed. In addition, the effectiveness of this system was verified by manufacturing multi-emulsion capsules with a size of 2.2 to 3 mm.

• 한국가시화정보학회지
• /
• 제12권2호
• /
• pp.13-17
• /
• 2014

In the present study, the optofluidic droplet manipulation in a microfluidic platform was demonstrated via theoretical and experimental approaches. Optical scattering force and gradient force were used to separate and trap droplets. Two types of droplets were generated by a T-junction method in the microfluidic channel. While they approach a test region where the optical beam illuminates the droplets, they were pushed by the optical scattering beam. The displacement by the laser beam is dependent on the refractive index of the droplets. By using the optical gradient force, the droplets can be trapped and coalesced. In order to bring the droplets in a direct contact, the optical gradient force was used to trap the droplets. A theoretical modeling of the coalescence was derived by combining the optical force and drag force on the droplet.

• Korean Chemical Engineering Research
• /
• 제57권1호
• /
• pp.58-64
• /
• 2019

본 연구는 주사기 바늘 기반의 미세유체 장치에서 균일한 polyethylene glycol diacrylate (PEGDA) 입자를 제조하는 새로운 방법을 소개한다. 미세유체 장치는 다양한 규격의 기성품들을 별도의 장비없이 조립하여 제작된다. 이 미세유체 장치에서 광개시제를 포함한 PEGDA 분산상과 오일의 연속상의 부피유속을 제어하여 단분산성 PEGDA 액적을 형성한다. PEGDA 액적은 장치의 말단에서 자외선 조사에 의해 입자로 중합된다. 입자의 크기는 부피유속과 미세유체 장치의 규격을 조절하여 손쉽게 제어되며 입자의 단분산도는 변동계수(coefficient of variation)값이 2.57%로 계산된다. PEGDA입자의 생물학적 응용을 증명하기 위해서 세포를 함입시키고 증식과 생존을 관찰한다.

• 산업기술연구
• /
• 제35권
• /
• pp.67-71
• /
• 2015

Various structures of particles were prepared by electrospray technique. In this research, solid particles were formed by electrospraying a solution of ethanol containing polyvinyl and tetraethyl orthosilicate. During the electrospray process, the ethanol solvent was evaporated, resulting in the solidification of precursors, forming solid particles. Evaporation of ethanol solvent also enhanced the mass transport which facilitated the development of porous and hollow structures.